1. Field of the Invention
The present invention relates to a display apparatus used in, for example, a television set, a personal computer, a word processor, office automation equipment, or the like, and more specifically, to a display apparatus incorporating a color filter substrate which can provide improved display quality.
2. Description of the Related Art
A liquid crystal display (hereinafter referred to as "LCD") apparatus is an exemplary display apparatus which adjusts the amount of transmitted light through an optical display medium in order to display images.
Conventionally, an LCD apparatus structure for displaying color images is known in which a color filter (hereinafter referred to as "CF") substrate is employed as one of a pair of substrates opposing each other with a liquid crystal layer interposed therebetween. This CF substrate includes color layer segments of red (R), green (G), and blue (B) on a transparent support, where the color layer segments may be arranged in stripes, dot patterns, etc., that correspond to the respective display pixels. A resin having an excellent transparency (e.g., an acrylic resin) may additionally be applied over such patterns of R, G, and B segments to provide a coating layer.
Moreover, for the purpose of providing improved contrast and/or display quality, a black mask (which may often be referred to as a "black matrix") is placed in a frame region (a peripheral region) which defines the circumference of a display region of the CF substrate, and/or in gaps between the pixels. The black mask, which may be formed by patterning a black paste layer or a black metal layer, is expected to exhibit a black state equivalent to a black display state.
For such a CF substrate, it has been desired to eliminate the production steps required for the black mask in order to lower the overall manufacturing cost. For example, the following methods are known to accomplish this: a method of alternately overlaying color layer segments of R and B (or R, G, and B) upon one another, these colors being selected to correspond to the respective colors of the color layer segments (R, G, and B) used in the display region so that they together exhibit a black state; and a method of employing a two-dimensional arrangement of color layer segments of R, G, and B where the color layer segments are provided with predetermined ratios so as to collectively exhibit a black state.
However, the latter method may generate moire fringes in the peripheral region. Specifically, when a CF substrate is adhered to an active matrix (hereinafter referred to as "AM") substrate, the color layer segments of the CF filter substrate may overlap a section of the AM substrate which is formed of a plurality of lead wires (e.g., gate lines (scan lines) and source lines (signal lines)), such section typically having a different reflectance from that of the surrounding glass substrate. etc. In such cases, moire fringes may be observed if the colors of the color layer segments in the "black mask" region vary In a cycle of more than about 100 .mu.m. This would result in the degradation of the display quality of the LCD apparatus.
In order to solve the aforementioned problem, Japanese Laid-open Publication No. 10-62768 discloses an LCD including a second light shielding section which covers a portion extending over two or more gate lines and/or over two or more source lines on an AM substrate. This arrangement ensures that the lead wire patterns will not be visually recognized, thereby improving the display quality. In addition, it is also disclosed that the second light shielding section can be formed of the same material as that of the gate and source lines so that the second light shielding section can be patterned simultaneously with the gate and source lines, thereby simplifying the production process.
In the conventional CF substrate described above, there is no predefined relationship between the arrangements of the gate/source lines on the AM substrate and the colors of the color layer segments on the CF substrate. Therefore, moire fringes may be generated in an extensional section (i.e., a section extending outside the display region) of lead wires in the frame region, thereby degrading the quality of the color display.
The technique disclosed In Japanese Laid-open Publication No. 10-62768, supra, requires additional steps for forming a second light shielding section, thereby increasing the number of steps performed during the production process. In the case where a second light shielding section is formed of the same material as that of the gate and source lines and the second light shielding section are patterned simultaneously with the gate and source lines in order to simplify the production process, some delay may possibly occur in the signal lines. Such delay may not be tolerated in certain applications.